In this paper, we present the theoretical investigation, design, and simulation of a new LiNbO3 guided-wave optical correlator suitable for real-time SAR applications. It is based on a complex interferometric structure, involving four aperiodic phase-reversal traveling wave modulators. The electrode structure is designed in order to reproduce the product signal between the received and reference voltages, which is then time-integrated by a suitable photodetector. The filtered signal outgoing from the detector is proportional to the final correlation function, which can be electronically registered and multiplexed on a two- dimensional matrix by sum-and-shift procedure. Thus, the processor performs the correlation function between the reference signal and the received signal when they are applied to the laser diode and to the electrodes as driving voltage, respectively. Comparisons between two different LiNbO3 waveguide fabrication techniques, i.e., proton exchange and titanium indiffusion, have been carried out in terms of circuit performances in order to reconstruct the SAR images.